Ralph Wiggum is a student who attends Springfield Elementary School. He is best known as the town's resident oddball, and has been immortalized for his non sequiturs and erratic behavior. His lines range from purely nonsensical, or bizarre interpretations of a current event, to surprisingly profound statements that go over people's heads. For this, Ralph is somewhat of an outcast among his peers, although he seems to be on good terms with a fair number of the other kids at school such as Bart, Lisa, and Milhouse.

The son of PoliceChief Clancy and Sarah Wiggum, Ralph is a good-hearted and generally well-meaning boy who suffers from either severe learning and social disabilities, or some other form of childhood psychiatric disorder. The nature of his mentality is kept rather ambiguous, much like many of the signature traits of much of the show's cast. Like almost every other character in Springfield, he may not be quite as simple as he first seems, as evidenced by his hinted immense potential as a performer.

Ralph is quite an enigma of a child. Upon first glance, one might mistake him for a child with dementia; or perhaps they might even look at him as a mentally challenged child. What is definite however, is that he suffers from learning disabilities of some sort, as evidenced by his apparently slow grasp of things in the world around him, his difficulty in studying, and his sporadic speech impediments. His unique manner of speech is often the source of the character's trademark random quotes, where Ralph may make a comment such as "What's a battle?", "It tastes like... burning!", or "Mr. Flanders, you're blindeded!," as well as his tendency to call his teacher "School Mommy" and on one occasion calling Superintendent Chalmers "Super Nintendo Chalmers".[4] However, Ralph is also able to speak in a normal manner much of the time, which only adds to the question of his condition and character. He also appears to have several talents. He is an incredible tap dancer and played the role of George Washington in the school play. As Washington, he not only recited his lines perfectly but also managed to play the role so well that he brought the audience to tears.[5] He is in his first year of second grade. He's also shown to be able to drive his dad's police car.

Ralph is often seen in very awkward situations such as eating paste, crayons, worms, knobs, lamps, and the Easter bunny and other such erratic forms of behavior that have since become a staple of the character. Ralph has a rather immense imagination, and is seemingly oblivious to the world around him. As such, he is generally a cheerful boy. However, Ralph also has a hint of tragedy and dark satire to him, like almost every other character on the show. Throughout the show's history, Ralph is eternally the odd one out among his peers at school. He has connections because his father is Chief of Police.

Ralph seems to generally get along with many people, as well as occasionally irritate and baffle them. After Lisa gave him a Valentine out of pity, Ralph developed a crush on her. Lisa publicly breaks up with him and Ralph is left devastated. The pair eventually become friends and Lisa has generally been nice toward him since.[5] Bart is rather long suffering of Ralph. On one occasion, Bart is forced by his mother Marge to play with Ralph. He is at first bored with Ralph but ends up having fun after they steal Clancy Wiggum's master key to the city, and Bart eventually admits that Ralph is a friend.[6] Ralph's relationship with his parents seems to be loving and affectionate. Clancy, in particular, rather adores his son as the two do much together, such as various road trips or Ralph's first trip to a major league baseball game.[7] Ralph can be quite a handful, however, and there are times where Clancy can be neglectful of his son as well. His favourite food is school supplies.

Ralph has a multitude of imaginary friends such as Wiggle Puppy and a pyromaniacal leprechaun being particularly well known among viewers. Ralph's teacher, Miss Hoover, is indifferent to his personality and his imagination. Though she will often correct him in a dull, condescending manner, ("The children are right to laugh at you, Ralph," she tells him at one point) she has yet to outright scold him. He usually misses the point.

Ralph was also part of a rather infamous hoax where Homer, Skinner, Apu, Lenny, Carl, Chief Wiggum and others had become so fed-up with the whole issue of voting early for the election that they decided to cast all of their votes to someone who was not only unbelievably small, but also so young and unbelievably unintelligent it would be impossible for him to be considered a candidate (and they ultimately chose Ralph). Ironically, Lisa discovers that Ralph is not only aware of what being nominated means, but is also taking the idea of being elected very seriously. Using his childish behavior, he intentionally manipulated the Republican and Democratic parties to join forces in their support of him.[8] He is best at sleeping and acting.

During class, Ralph's teacher Miss Hoover will stop lecturing the class for a moment to question Ralph's actions such as eating something he shouldn't, or saying something bizarre or oblivious. Another common 'Ralph' moment is that Ralph will be at a major event, and will say something to either perplex everyone present or point out something so glaringly obvious it's funny. Ralph has quite a knack for getting himself into sticky situations as well. Examples of Ralph moments include him gorging himself with chocolate,[9] being profiled by a scary dentist,[10] pretending to be a firetruck,[11] pretending he is an imaginary puppy see This Little Wiggy, and proclaiming that he will attend "Bovine University".[12] He has been shown wetting himself in public.[13] Similarly, in the future, he can be seen talking to a classmate by the punchbowl, saying "I can use the potty now.".[14] Also, Skinner looked at the building sadly and remembers touching moments with kids saying things like "I know how to read" and "Thank you, Principal Skinner". Ralph's distinctive voice saying "Principal Skinner, I got carsick in your office", is heard.[15] This seems to have subsided a little recently, although appearances by Ralph himself have been lighter. Ralph has also demonstrated signs at being borderline psychotic, as he has stated that there is a rock in his yard, where he saw a leprechaun, who told him to burn things. When he later helps save the Mayor of Springfield with Bart and Lisa, the leprechaun appears and tells him, "You've done grand laddie. Now you know what you have to do? Burn the house down! Burn them all!" with Ralph smiling vacantly and nodding in agreement.[6]

Ralph's behavior may be explained in part by the fact that when he was a baby, his father dropped him on his head. After that, Ralph had trouble bringing a baby bottle to his mouth.[16]

When Ralph saw Bart skateboarding naked, he said, "I like men now!" [17]

Ralph has shown to have an occasional friendship with Bart. Bart stood up to bullies who were bullying him and befriended Ralph as a result of this and befriended him after finding out about all the cool police stuff he had in his house.[6] Ralph has also been invited to a party for Bart by Marge, and Bart insulted him, causing him to run off crying.

Ralph appears along with Rod and Todd Flanders as Hobbit-like children who help Homer and Marge defeat the two-headed dragon in order to get the keycard.[19] He also appears as a holder of one of the three Sparklemon that Homer and Lisa must defeat.[20] At the end of the game, he is seen watching the closing moments of the Simpsons family talking with God, then he sees the player and says "Daddy... someone's looking at me...".

In Ralph's first credited appearance in the show was the episode "Moaning Lisa", he was considerably different in both appearance and behavior from his later appearance, although he also briefly appeared in the first episode" Simpsons Roasting on an Open Fire".
Ralph's signature use as a character in the show is to deliver either an odd bit of behavior, or dialogue which either perplexes others or merely gives the audience a quick laugh. Originally intended to be a "Mini-Homer", Ralph eventually took on a life of his own. The staff figured that he'd also fit perfectly as the son of Chief Wiggum, a fact made canon in "I Love Lisa", (although he is referred to by his last name of Wiggum in "Kamp Krusty" before). Ralph was named after comedian Jackie Gleason's character on The Honeymooners Ralph Kramden. Matt Groening considers any lines for Ralph "really hard to write."

With a combination of his popular commentary and his endearingly innocent character, Ralph eventually became one of the show's most popular characters. Ralph's popularity as a character has even spread so far that the rock band The Bloodhound Gang made a song called "Ralph Wiggum," dedicated to the character and comprised solely of some of his most famous quotes for lyrics. The song can be found on their album Hefty Fine. Another band, Trillium Circle has a member named Ralph Wiggum, presumably a pseudonym. Ralph also became a prominent pop-culture figure in the 2008 U.S. Presidential election after the episode "E Pluribus Wiggum" aired in January 2008.

Show creator Matt Groening has stated that Ralph is one of his personal favorite characters on The Simpsons, and whenever someone asks who writes specific characters (a common misconception about the writing process), writers will most likely take credit for writing for Ralph.[1]

The character from Diary of a Wimpy Kid, Rowley Jefferson bears similarities to Ralph in terms of appearance and personality.